But the great white whale for some of these solar developers is deploying floating photovoltaic arrays on the California Aqueduct, the 400-mile long canal that irrigates much of the state’s agricultural heartland and delivers water to Southern California.

“It’s a dream for us,” said Phil Alwitt, project development manager for SPG Solar, a Novato, Calif., company that has built floating solar arrays for winery irrigation ponds.

The idea is to reduce evaporation while producing electricity to offset the power consumed by the massive pumps that move water through the aqueduct. Solaris Synergy, an Israeli company, estimates that its floating solar system could generate two megawatts per mile of the aqueduct.

“You could generate gigawatts from all that unused space on the California Aqueduct and there’s a huge electricity demand,” said Danny Kennedy, co-founder of Sungevity, an Oakland, Calif., solar installer. Read more…

Peter DaSilva for The New York TimesRecycling bins are one of the environment-friendly features of Terminal 2 in San Francisco.

In Tuesday’s Times, I wrote about San Francisco International Airport’s renovated Terminal 2 and efforts to make flying a less carbon-intensive and stressful experience.

The art-filled terminal, known as T2, features Danish modern furniture, organic chow, 350 power outlets, free Wi-Fi and other creature comforts and innovations designed to cut the building’s energy footprint while making air travel, dare we say it, more fun.

The terminal reflects the techno-cool sensibility of Virgin America, which shares the space with American Airlines. Virgin has attracted a youngish hip clientele with a fleet of Airbuses that have neon mood lighting, a nightclub soundtrack and seatback touch screens that enable passengers to order food and entertainment.

Airport authorities are seeking LEED gold status for T2 because of the reductions in its energy and water consumption. If granted, T2 would become the first airport terminal to achieve such a rank, which the Green Building Council awards according to a point system.

Not all of T2’s green attributes are visible to passengers. Virgin, for instance, intends to apply for LEED Platinum status, a higher ranking, for the commercial interiors for its crew quarters hidden below the gate areas.Read more…

As I wrote in Thursday’s Times, several start-ups backed by Silicon Valley venture capital firms are developing a new type of internal combustion engine that promises a striking boost in fuel economy while reducing greenhouse gas emissions.

It sounds a bit too good to be true, but the companies have had their claims verified by independent firms, and some of them have signed licensing deals with major engine manufacturers.

The start-ups that I profiled – Achates Power, EcoMotors and Pinnacle Engines – all are building variations on what is called an opposed piston engine. Such engines do away with heavy cylinder heads that serve as combustion chambers in conventional engines. Instead, the space between two opposing pistons forms the combustion chamber where fuel is ignited.

That makes opposed piston engines lighter and cheaper to make. And because opposed piston engines have a greater power density, they waste less energy as heat and thus operate more efficiently.Read more…

George P. Shultz, the Republican former secretary of state, and Thomas F. Steyer, the Democratic hedge fund billionaire, are reviving the coalition that campaigned last year to defeat Proposition 23, the California ballot measure that would have derailed the state’s’ landmark global warming law.

Their new organization, Californians for Clean Energy and Jobs, will push for greater investment in green technology and the enforcement of the global warming law, known as A.B. 32, according to Mr. Steyer, founder of Farallon Capital Management in San Francisco.

“We’re going to be fighting to make sure it is implemented in a way that not just creates businesses here, but the jobs stay here, and we get the kind of growth that will show the country that this way of thinking is intensely practical and real world,” Mr. Steyer said on Friday at a news conference.

“I hate to say we’re getting the band back together, but we’re getting the band back together,” he added.Read more…

Among the standard features offered for new homes at Manzanita at Paseo del Sol, a KB Home development in a desert suburb southeast of Los Angeles, are nine-foot ceilings, six-panel doors and a 1.4-kilowatt solar array.

While KB Home has offered rooftop photovoltaic panels as an option for some time, the home builder now will make solar arrays from SunPower standard equipment on more than 800 homes in 10 communities being built in Southern California.

“This is a game changer for our industry and a powerful way for us to compete in the marketplace, especially with resale homes,” Craig LeMessurier, KB Home’s director of corporate communications, said in an e-mail. While pricey solar panels are often found on the roofs of high-end houses, it’s notable that KB Home is installing the arrays on homes with base selling prices that range from $250,000 to $360,000. In California, that’s starter home territory.Read more…

European Pressphoto AgencyConstruction vehicles and workers excavate a site for a nuclear reactor at Plant Vogtle in Waynesboro, Ga., that is to be built with help from a federal loan guarantee.

With many riveted on Japan’s reactor crisis, the head of the Department of Energy’s loan guarantee program has affirmed that it will continue to finance nuclear projects in the United States.

“Assuming there is a desire in the Capitol to move forward, nuclear remains an important part of the energy mix,” Jonathan Silver, executive director of the Energy Department’s loan programs office, said on Wednesday in a presentation at the Cleantech Forum conference in San Francisco.

“I point out here that the technology at use in the project we financed is quite different from the ones that have been affected by Japan,” he added. “Nonetheless, we obviously take this quite seriously.”

Mr. Silver’s remarks followed Congressional testimony in Washington by Energy Secretary Steven Chu and Gregory B. Jaczko, chairman of the Nuclear Regulatory Commission. Dr. Chu said that the Obama administration continued to support nuclear energy, noting the president had requested that $36 billion be appropriated for the nuclear loan guarantee program.Read more…

For years, Mr. Steyer, a billionaire San Francisco hedge fund manager, assiduously maintained a low profile while becoming a major donor to Democratic candidates. That changed in 2010 when he led the successful fight to defeat Proposition 23, a California ballot measure backed by two Texas oil companies and a company controlled by Charles G. and David H. Koch, the secretive billionaire brothers and bankrollers of conservative causes.

Bloomberg NewsThomas F. Steyer

Proposition 23 would have effectively derailed the state’s landmark global warming law, which would have been a big setback for California’s blooming green technology industry. Mr. Steyer, the founder of Farallon Capital Management, is the main financial backer of Greener Capital, a venture firm that invests in renewable energy start-ups.

Now Mr. Steyer appears to be itching to take on the Koch brothers and their supporters as Republican lawmakers seek to limit the United States Environmental Protection Agency’s ability to regulate greenhouse gas emissions. “As an investor who one might say is insanely obsessed with energy and its generation and use around the world, it seems crazy to me we would roll back science-based clean air standards because there are skillful political operatives and wealthy political donors who really want to get rid of E.P.A. regulations,” he said in a speech Monday evening at the Cleantech Forum conference in San Francisco. “That seems nuts to me.”Read more…

First there was music sharing and then car sharing. Now get ready for plug sharing.

PlugShare

Xatori, a Silicon Valley software start-up, aims to create a network of electric car enthusiasts who make their household power outlets and home chargers available for drivers who need to top off their battery or who find themselves out of range of the few public-charging stations currently available.

On Monday, Xatori released PlugShare, a free iPhone app that lets drivers and outlet owners locate and offer electricity.

“We want to break down that barrier in people’s minds about where it’s acceptable to charge,” said Armen Petrosian, Xatori’s co-founder and chief technology officer. “We think the infrastructure to charge is everywhere.”Read more…

As I wrote in Thursday’s Times, the fate of several multibillion-dollar solar thermal power plants to be built the Southern California desert is in question as conservationists and other groups sue to stop the projects largely on environmental grounds.

The five lawsuits currently pending against five solar thermal projects licensed by the state and approved for construction on federal land represent a multiplicity of interests.

The Sierra Club, for instance, has petitioned the California Supreme Court to overturn a license issued for the Calico Solar Energy Project, which the environmental group argues would harm the imperiled desert tortoise and other wildlife. A labor group, California Unions for Reliable Energy, also filed a petition on similar grounds. Read more…

Suntech, the Chinese solar giant, has won a contract to supply photovoltaic panels for a 150-megawatt project in Arizona, marking China’s entry into a lucrative United States power-plant market dominated by American companies.

The project is the first phase of a planned 700-megawatt project called Mesquite Solar to be built about 40 miles west of Phoenix and operated by Sempra Generation, a subsidiary of Sempra Energy. A California utility, Pacific Gas & Electric, will buy the electricity produced by the power plant’s first phase, called Mesquite Solar 1.

As photovoltaic panel prices have plummeted in recent years, utilities have increasingly turned to developers to build massive megawatt projects. American companies like First Solar of Tempe, Ariz., and Silicon Valley’s SunPower have captured the bulk of those contracts.Read more…

Taking a page from the solar industry, Bloom Energy on Thursday unveiled a service to allow customers to buy the electricity generated by its fuel cells without incurring the capital costs of purchasing the six-figure devices.

The company is introducing its Bloom Electrons service nearly a year after the once-secretive Silicon Valley start-up unveiled its Bloom Energy Server, a 100-kilowatt solid oxide fuel cell at a news conference that offered testimonials from Arnold Schwarzenegger, then the California governor; Colin Powell, the former secretary of state; and top executives from Google, Wal-Mart and eBay.

Fuel cells, which convert hydrogen, natural gas or another fuel into electricity through an electrochemical process, have long held out the promise of cheap and plentiful energy while emitting fewer pollutants than conventional power plants.

But the $700,000 to $800,000 cost of the ‘Boom Box’ has proven steep for potential customers other than the Fortune 500 companies that have bought the sleek metallic cubes.Read more…

AQT Solar, via Business WireThe building in Blytheville, S.C., where AQT Solar’s second solar factory will be opened. It already has one in Sunnyvale, Calif.

As American solar companies face intense competition with low-cost Chinese manufacturers, a Silicon Valley photovoltaic cell maker has announced that it will open a huge factory in South Carolina.

AQT Solar’s plant is to be installed in phases in an existing 184,000-square-foot building in Blythewood, north of Columbia. By the end of 2014, the thin-film solar factory will have an annual manufacturing capacity of 1,000 megawatts and employ up to 1,000 workers, said Michael Bartholomeusz, chief executive of the company, a Sunnyvale, Calif., start-up.

The plant will be one of the few big solar factories to be created in the United States in recent years without a federal loan guarantee and reflects a move to slash capital costs to compete with China.

“We’re not commenting on the specifics of our finances but can say that we have the capital resources to facilitate this build-out,” said Mr. Bartholomeusz, who founded AQT in 2008. “If you look at employee heads per megawatt, we’re running extremely resource-lean.”Read more…

Todd WoodySolar mirrors suspended on stamenlike struts at an installation in Davis, Calif.

In an article in the special Energy section of The New York Times on Wednesday, I write about a developer who wants to sell “garden plots” in a 15-megawatt photovoltaic farm in Davis, Calif., so that residents can go solar without having to cut down trees in the city’s urban forest to install rooftop arrays.

While solar power plants seem like a 21st-century phenomenon, the Davis project dates from 1987, when the utility Pacific Gas and Electric built P.V.U.S.A. — Photovoltaics for Utility Scale Applications –- to test various nascent technologies.

Matt Cheney, a veteran renewable financier in San Francisco and founder of CleanPath Ventures, eventually acquired P.V.U.S.A. and received the city’s blessing to expand the power plant from around one megawatt to 15 megawatts.

Last week, I took a took a tour of the solar farm, a veritable outdoor Smithsonian of solar power displaying a dozen photovoltaic technologies. Some have become common sights on rooftops and at power plants while others barely left the laboratory before failing and bear the name of start-ups long gone. Read more…

Todd WoodyMercy Vaughn, a wildlife biologist, with a desert tortoise on the Ivanpah solar power plant site.

In an article in The New York Times on Wednesday, I write about how the fortunes of big solar power plants in the desert Southwest can hinge on the way developers handle imperiled wildlife in the path of their projects.

The protected desert tortoise has become the totemic animal for environmentalists fighting to ensure that the huge solar farms don’t eliminate essential habitat for the long-lived reptile and other wildlife, like the bighorn sheep and flat-tailed horned lizard.

The tortoise has been in decline for decades, and the rampant changing of the desert — including the development of casinos, strip malls and subdivisions, and designation of off-road recreational vehicle areas — took its toll long before construction began late last month on the Ivanpah solar power plant, the first large-scale solar thermal project to be break ground in the United States in 20 years.

Still, the solar farms will industrialize the desert on an unparalleled scale. The seven projects already licensed in California will cover 42 square miles with immense mirror arrays. Read more…

Todd Woody for The New York TimesA prototype of the Suncatcher at the Sandia National Laboratories in New Mexico gives a rough idea of the sheer scale of Tessera’s proposed Calico project in the California desert.

In an article in Friday’s paper, I write about the solar thermal power plant building boom now under way in California’s Mojave Desert. The looming expiration of crucial federal financial support for the multibillion-dollar projects, though, could turn the boom to bust.

But that hasn’t deterred California regulators, who on Thursday approved the seventh large-scale solar thermal farm since late August.

After years of painstaking environmental review, the California Energy Commission has been green-lighting the massive solar power plants at warp speed so developers can break ground before year’s end and qualify for a government cash grant that covers 30 percent of the cost of construction.

The latest approval goes to Tessera Solar’s Calico project, to be built in the San Bernardino County desert in Southern California. Originally proposed to generate 850 megawatts -– at peak output, that’s close to the production of a nuclear power plant -– the project was whittled down to 663.5 megawatts to lessen the impact on wildlife like the desert tortoise and the bighorn sheep. Read more…

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How are climate change, scarcer resources, population growth and other challenges reshaping society? From science to business to politics to living, our reporters track the high-stakes pursuit of a greener globe in a dialogue with experts and readers.